Examples of discharge containers containing liquid contents and discharging such contents therefrom include a squeeze container. Squeeze containers can be classified as squeeze containers provided with a nozzle cap, squeeze containers provided with a squeeze foamer and the like, according to the kind of cap attached to the container body.
To complete a product using such a squeeze container, it is necessary to select from among various kinds of materials, shapes and the like depending on the physical properties of the contents and the intended use and the like, and then draw up a design based on the discharge amount per one discharge, the discharge mode, i.e., whether the contents are discharged as a liquid or a foam, the discharge frequency and the like. Such selection and design requires a large amount of work and in new product development often entails great difficulties, even if carried out with the cooperation of people skilled in the art of containers and in the art of the contents.
For example, a face wash cosmetic is used approximately several times per day in an amount of about 1 g each time. Thus, the conditions required for a container containing a face wash cosmetic are that it can be left for a period of several months to several years with its contents inside, and the discharge mode can be a liquid or in a fine foam. Accordingly, it is necessary to select the optimum materials for those conditions and draw up a design based thereon.
On the other hand, two-part hair dye or bleach compositions are constituted of a first agent containing an alkaline agent and a second agent containing hydrogen peroxide. Such compositions have to be used by thoroughly mixing the first and second agents just before use. In addition, all of the composition needs to be used up immediately after mixing. Furthermore, a mixed solution of the first and second agents has to be applied on the hair and then left for about 30 minutes, during which time the mixed solution must not drip. Therefore, to apply the mixed solution on the hair in a liquid state as is, the mixed solution needs to be in the form of a gel or a cream having a viscosity of at least several thousand mPa·s. Considering the ease of applying on the hair and problems such as corrosion of the container by the composition, a squeeze container provided with a nozzle cap is generally used for containing such a form of a two-part hair dye or bleach composition.
However, to carry out dyeing or bleaching without any unevenness using a gel- or cream-formed two-part hair dye or bleach composition, since the mixed solution has a high viscosity as mentioned above, not only skill is required, but the hair must be “pre-blocked” (braiding the hair into sections at the front, sides and rear of the head). Thus, a lot of time and effort is required to carry out such dyeing or bleaching.
In recent years, to resolve this problem, two-part hair dye or bleach compositions have been proposed which contain a foaming agent in at least one of the first or second agents (Patent Documents 1 and 2). If the mixed solution of these first and second agents is applied on the hair by discharging it in a foam by a foamer container, dyeing or bleaching can be carried out simply without any trouble.    Patent Document 1: JP-A-2004-339216    Patent Document 2: JP-A-2006-124279